Sigtronics SCI-6 User Manual

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OPTION - PILOT TRANSMIT PRIORITY - If the pilot and the
copilot key at the same time (not a common occurrence) the
default operation is that both microphones will go out the aircraft
radio to the tower. If you prefer only the pilot’s microphone active
when both press their PTT’s simultaneously then enable this
option. Note - if only one of the pilots presses his PTT only his
mic will go out over the radio regardless if this option is selected

or not.

To enable this option,
remove the four screws
on the bottom of the
SCI unit and remove
the cover. Refer to
Figure 1. To enable
pilot transmit priority
solder a small jumper
between pad “B” and
pad “G”. Replace the
cover and the four
screws and tighten.
Removing this jumper
will

deactivate

the

option.

CHASSIS INSTALLATION

To upgrade an existing SPA-400 installation to a SCI-4 or a SPA-
600 to SCI-6 skip to the “UPGRADING A SPA INSTALLATION TO A
SCI” section on page 4. For a completely new intercom installation
continue below.

HARDWARE SUPPLIED

Besides the intercom unit and these instructions, each SCI system
comes with the following hardware:

SCI-4

SCI-6

Headphone Output Jacks - Accept standard
0.250” aircraft headphone plugs.

Microphone Input Jacks - Accept standard
0.206” aircraft microphone plugs. (U93 plug
compatible jacks can be used in place of the
jacks provided).

Mic Jack Insulating Washers, Flat

Mic Jack Insulating Washers, Shoulder

Intercom Panel - lettered on both sides.

Intercom Control Knobs

Mounting Screws 4-40 x 1/2

Drill Template - Adhesive backed hole size
pattern for drilling aircraft panel.

Aircraft/Intercom Interface Cable (4 feet long)

Headphone/intercom Interface Cable (4 feet

long)

UNIT PLACEMENT

The SCI unit has been designed to mount either horizontally or
vertically in your aircraft panel.
The location selected for the SCI unit requires a minimum front
panel area of 2 1/2” by 1”. Depth required behind panel is 6” plus
cable access.

CAUTION: Move the aircraft flight controls through the limits of
travel while observing the selected area and making sure that the
rear of the intercom and cable will not interfere with any aircraft
control components.

PANEL PREPARATION:

1. Position the adhesive drill template on the aircraft panel in the

selected area.

2. Center punch each hole at the cross lines. (Five holes are in a

straight line and equally spaced 0.4” apart, two holes are 0.8”
apart).

3. Drill 1/8” pilot holes in all seven places.

4. Enlarge two holes to 9/16”, one hole to 7/16”, and two holes to

3/16” per the template.

MOUNTING CHASSIS (See Figure 2)

1. Remove the knobs from the Volume and Squelch controls using

a 0.050” Allen wrench. NOTE: DO NOT REMOVE the nuts from
the Volume/Squelch, or ALL/ISO/CREW controls.

2. Insert the SCI unit from the rear of the aircraft panel with the

appropriate arrow on the unit chassis pointing upwards. Make
sure the squelch indicator lights have unrestricted movement
through aircraft panel.

3. Install the printed SCI panel and lightly thread the two 4-40

screws through the holes in intercom panel. The nuts on the
Volume/Squelch and OFF/ALL/ISO controls will fit inside the
9/16” and 7/16” diameter holes.

4. Tighten the two screws.

5. Install the knobs on the Volume (VOL) and Squelch (SQL)

control shafts and tighten the Allen screws.

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This manual is related to the following products:

SCI-4